Investigation of the Similarity Law in Discharges at High Pressure Using A Kinetic Global Model

A kinetic global model framework (KGMf) has been developed and used to investigate the similarity law in discharges at high pressure. Keeping the pd (gas pressure $\times $ linear dimension) unchanged, the electron and ion densities in the steady state are calculated while the geometrical similar volume increases from micron scale $(500 ~\mu \mathrm {m})$ to millimeter scale (2.5mm) and at the pressure decreases from 760Torr to 152Torr, correspondently. In the model, electrons, positive ions and fourteen excited levels of argon atom are considered, and the transition of excitations, three-body collisions, and stepwise ionizations, which are forbidden processes from the similarity law are included and excluded, respectively1–3. The simulation results showed that within the forbidden processes the normalized density relations are below the predicted relations from the similarity law, which is attributed to the nonlinear impact of forbidden processes. Without the forbidden processes, the parameter relations are in good agreement with the theoretical prediction from the similarity law. The KGMf has the potential for deeper studies on similarity law at high pressure, such as gas mixtures with other volume and surface processes.